Aluminum/Graphene Thermal Interface Materials with Positive Temperature Dependence

Graphene is widely used in excellent thermal interface materials (TIMs), thanks to its remarkably high in-plane thermal conductivity (k_∥). However, the poor through-plane thermal conductivity (k_⊥) limits its further application. Here, we developed a simple in situ growth method to prepare graphene-based thermal interface composites with positively temperature-dependent thermal conductivity, which loaded aluminum (Al) nanoparticles onto graphene nanoplatelets (GNPs). To evaluate the variations in thermal performance, we determined the thermal diffusivity and specific heat capacity of the composites using a laser-flash analyzer and a differential scanning calorimeter, respectively. The Al nanoparticles act as bridges between the nanoplatelets, enhancing the k_⊥ of the 1.3-Al/GNPs composite to 11.70 W·m^-1·K^-1 at 25 °C. Even more remarkably, those nanoparticles led to a unique increase in k_⊥ with temperature, reaching 20.93 W·m^-1·K^-1 at 100 °C. Additionally, we conducted an in-depth investigation of the thermal conductivity mechanism of the Al/GNPs composites. The exceptional heat transport property enabled the composites to exhibit a superior heat dissipation performance in simulated practical applications. This work provides valuable insights into utilizing graphene in composites with Al nanoparticles, which have special thermal conductivity properties, and offers a promising pathway to enhance the k_⊥ of graphene-based TIMs.